Managing the Nitrogen economy of bacteria

我们计划解决植物生长的一种关键营养物质的供应--植物可以吸收的形式的氮(即氨)--如何由土壤中的细菌提供。植物缺乏氮素供应往往会限制它们的生长，而使用化学生产的氮肥会威胁环境，而且生产的能源成本很高。因此，提供固定氮素的替代方法是可取的，这些方法既不依赖化石燃料，也不依赖于在土壤中使用化学物质。我们计划研究如何通过控制系统网络来建立简单土壤细菌的氮经济，以实现细胞内氨的最佳水平，并对这些控制系统进行改造，从而允许氨或氨基酸出口到土壤，从而出口到植物。氨气是通过细菌固氮酶的作用产生的，我们将研究细菌细胞如何调节这一代谢过程，以最大限度地提高自身的资源利用效率。这一知识将使我们能够为提高农业生产力的目的重新连接监管控制。到目前为止，已经进行了一些简单的首次尝试来利用细菌氨出口来促进植物生长，有些令人惊讶的是，这些一次性尝试显示出希望，因为从细菌中减少的氮正在变得可用于支持植物生长。因此，细菌成功地提炼氨出口具有很大的前景。我们的工作要求我们准确地量化用于确定细胞氮经济的各种关键小分子和蛋白质，并制定一种方案，通过这种方案，我们可以干预并创造一种情况，即一些由氮素衍生的氨从细菌细胞中排泄到外部，而不会大大牺牲固氮细菌的生长和适合性。为此，我们将使用捕捉控制系统不作为的各种参与者的方法，使我们能够计算出监管的要点发生在哪里，以及如何对其进行修改以获得氨输出功能，而不会失去有机体的适应性。这一方法要求我们将实验与氮素控制方案的建模相结合，并部署合成生物学工具来产生新的主代调控蛋白，这将使我们能够捕获对细胞管理其氮素经济所需的整个复杂基因网络的控制。通过将这些方法与关于土壤寄生细菌如何与植物根部建立密切联系并具有竞争性的知识和平行研究相结合，特别是它们如何从植物中获得碳作为能源，我们有望能够以可持续的方式改善植物的氮素供应，以提高作物产量。此外，我们计划利用在该项目中获得的知识和理解，开发完全由太阳能驱动的含氮化学品的工业化生产的可再生生物技术。

We plan to address how the supply of one key nutrient for plant growth - nitrogen in a form that can be taken up by plants(i.e. ammonia) - can be supplied by soil dwelling bacteria. A lack of nitrogen supply to plants frequently limits their growth,and the use of chemically produced nitrogen fertilizers threatens the environment and is energetically expensive toproduce. Hence alternative methods to supply fixed nitrogen that are not dependent on fossil fuels or the application ofchemicals to the soil are desirable. We plan to investigate how the nitrogen economy of simple soil dwelling bacteria isestablished through the network of control systems operating to achieve optimal levels of ammonia within cells, and tomodify these control systems to then allow the export of ammonia or amino acids to the soil and hence to plants. Ammoniawill be produced by the action of the bacterial nitrogen fixing enzyme nitrogenase, and we will work out how the bacterialcell regulates this metabolic process in order to maximize its own resource use efficiency. This knowledge will allow us torewire the regulatory control for the purpose of enhancing agricultural productivity.To date some simple first pass attempts have been made to exploit bacterial ammonia export for plant growth, and somewhat surprisingly these one offs show promise in that plant growth is enhanced in a manner suggesting reduced nitrogen from the bacteria is becoming available to support plant growth.Hence successfully refining ammonia export by bacteria holds great promise.Our work requires that we accurately quantify various key small molecules and proteins used to determine the cellsnitrogen economy, and produce a scheme whereby we can intervene and create a situation where some of the nitrogenasederived ammonia is excreted from the bacterial cells to the outside without greatly sacrificing the growth and fitness of thenitrogen fixing bacteria. To do so we will use methodologies which capture the various players of the control systems inaction, allowing us to work out where the major points of regulation occur and how they might be modified to gain anammonia export function without losing the fitness of the organism. This approach requires that we combine experimentswith modelling of the nitrogen control schemes, and also deploy synthetic biology tools to produce new master generegulator proteins which will allow us to capture the control of the entire complex networks of genes needed for the cellsmanagement of its nitrogen economy. By combining these approaches with knowledge and parallel study of how soil dwelling bacteriaestablish close associations with plant roots and are competitive , and in particular how they gain carbon as an energy source from plants, weexpect to be able to in a sustainable way improve nitrogen supply to plants in order to improve crop yields. In addition, weplan to utilize the knowledge and understanding that is gained in this project to also develop renewable biotechnologicalprocesses for industrial production of nitrogen containing chemicals that is driven entirely by solar energy.